Skip to content

Smarter pruning during the recursive subdivision during climate generation #3372

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
IntegratedQuantum merged 1 commit into from
Jul 17, 2026
Merged

Smarter pruning during the recursive subdivision during climate generation #3372

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
88 changes: 59 additions & 29 deletions src/server/terrain/climategen/NoiseBasedVoronoi.zig
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,20 @@ const GenerationStructure = struct {
return x*x*(3 - 2*x);
}

fn findClosestBiomeTo(prefilteredCandidates: []*BiomePoint, wx: i32, wy: i32, relX: i32, relY: i32, worldSeed: u64) BiomeSample {
fn interpolationValueBetween(biome1: *const BiomePoint, biome2: *const BiomePoint, pos: Vec2i) f32 {
const dist = biome1.voronoiDistanceFunction(pos);
const dist2 = biome2.voronoiDistanceFunction(pos);
const totalDist = dist + dist2;
const interpolationStrength = 0.5;
const centerPos = totalDist*0.5;
const interpolationStart = centerPos - interpolationStrength*0.5;
const interpolationEnd = centerPos + interpolationStrength*0.5;
if (dist < interpolationStart) return 0;
if (dist > interpolationEnd) return 1;
return smoothInterpolation((dist - interpolationStart)/(interpolationEnd - interpolationStart));
}

fn findClosestBiomeTo(prefilteredCandidates: []const *const BiomePoint, wx: i32, wy: i32, relX: i32, relY: i32, worldSeed: u64) BiomeSample {
const x = wx +% relX*terrain.SurfaceMap.MapFragment.biomeSize;
var y = wy +% relY*terrain.SurfaceMap.MapFragment.biomeSize;
if (@mod(relX, 2) == 1) y += terrain.SurfaceMap.MapFragment.biomeSize/2;
Expand All @@ -221,33 +234,26 @@ const GenerationStructure = struct {
var hills: f32 = 0;
var mountains: f32 = 0;
var totalWeight: f32 = 0;
// all BiomePoints are within ±2 chunks of the current one.
var candidateList: main.List(struct { point: *BiomePoint, weight: f32 }) = .initCapacity(main.stackAllocator, prefilteredCandidates.len);

var candidateList: main.List(struct { point: *const BiomePoint, weight: f32 }) = .initCapacity(main.stackAllocator, prefilteredCandidates.len);
defer candidateList.deinit(main.stackAllocator);
for (prefilteredCandidates) |candidate| {
candidateList.appendAssumeCapacity(.{.point = candidate, .weight = 1});
}
// Interpolate between all pairs of biomes.
var i: usize = 0;
outer: while (i < candidateList.items.len) {
const dist = candidateList.items[i].point.voronoiDistanceFunction(.{x, y});
var j = i + 1;
while (j < candidateList.items.len) {
const dist2 = candidateList.items[j].point.voronoiDistanceFunction(.{x, y});
const totalDist = dist + dist2;
const interpolationStrength = 0.5;
const centerPos = totalDist*0.5;
const interpolationStart = centerPos - interpolationStrength*0.5;
const interpolationEnd = centerPos + interpolationStrength*0.5;
if (dist < interpolationStart) {
const interp = interpolationValueBetween(candidateList.items[i].point, candidateList.items[j].point, .{x, y});
if (interp == 0) {
_ = candidateList.swapRemove(j);
continue;
}
if (dist > interpolationEnd) {
if (interp == 1) {
_ = candidateList.swapRemove(i);
continue :outer;
}
const interp = smoothInterpolation((dist - interpolationStart)/(interpolationEnd - interpolationStart));
candidateList.items[i].weight *= 1 - interp;
candidateList.items[j].weight *= interp;
j += 1;
Expand Down Expand Up @@ -435,10 +441,45 @@ const GenerationStructure = struct {
}
}

fn pruneInterpolationCandidates(allocator: NeverFailingAllocator, wx: i32, wy: i32, wxMax: i32, wyMax: i32, candidates: []const *const BiomePoint) []const *const BiomePoint {
var result: main.List(*const BiomePoint) = .empty;

// Check interpolation between all pairs of biomes.
outer: for (candidates) |candidate| {
if (candidate.pos[0] >= wx and candidate.pos[0] < wxMax and candidate.pos[1] >= wy and candidate.pos[1] < wyMax) {
result.append(allocator, candidate);
continue;
}
var i: usize = 0;
while (i < result.items.len) {
blk: {
const interp1 = interpolationValueBetween(candidate, result.items[i], .{wx, wy});
if (interp1 != 0 and interp1 != 1) break :blk;
const interp2 = interpolationValueBetween(candidate, result.items[i], .{wx, wyMax});
if (interp2 != interp1) break :blk;
const interp3 = interpolationValueBetween(candidate, result.items[i], .{wxMax, wy});
if (interp3 != interp1) break :blk;
const interp4 = interpolationValueBetween(candidate, result.items[i], .{wxMax, wyMax});
if (interp4 != interp1) break :blk;
if (interp1 == 0) {
_ = result.swapRemove(i);
continue;
} else {
continue :outer;
}
}
i += 1;
}
result.append(allocator, candidate);
}

return result.toOwnedSlice(allocator);
}

const margin = chunkSize >> terrain.SurfaceMap.MapFragment.biomeShift;
const preMapSize = ClimateMapFragment.mapEntrysSize + 2*margin;
pub fn fillRecursively(wx: i32, wy: i32, preMap: *[preMapSize][preMapSize]BiomeSample, biomeCandidates: []*BiomePoint, worldSeed: u64, relX: i32, relY: i32, width: u31, height: u31) void {
if (width <= 1 or height <= 1) {
pub fn fillRecursively(wx: i32, wy: i32, preMap: *[preMapSize][preMapSize]BiomeSample, biomeCandidates: []const *const BiomePoint, worldSeed: u64, relX: i32, relY: i32, width: u31, height: u31) void {
if (width < 8 or height < 8) {
for (0..width) |dx| {
const indexX = @as(usize, @intCast(relX + margin)) + dx;
for (0..height) |dy| {
Expand All @@ -451,8 +492,6 @@ const GenerationStructure = struct {
// Subdivide
const halfWidth = width/2;
const halfHeight = height/2;
var newCandidates: main.List(*BiomePoint) = .initCapacity(main.stackAllocator, biomeCandidates.len);
defer newCandidates.deinit(main.stackAllocator);
for (0..2) |dx| {
for (0..2) |dy| {
const newRelX = relX + if (dx == 0) 0 else halfWidth;
Expand All @@ -465,18 +504,9 @@ const GenerationStructure = struct {
const wyMin = wy +% newRelY*terrain.SurfaceMap.MapFragment.biomeSize;
const wyMax = wyMin +% newHeight*terrain.SurfaceMap.MapFragment.biomeSize +% terrain.SurfaceMap.MapFragment.biomeSize;

newCandidates.clearRetainingCapacity();
for (biomeCandidates) |candidate| {
const influenceRadius = 3*@as(i32, @ceil(candidate.radius));
const candidateMinX = wxMin -% influenceRadius;
const candidateMaxX = wxMax +% influenceRadius;
const candidateMinY = wyMin -% influenceRadius;
const candidateMaxY = wyMax +% influenceRadius;
if (candidate.pos[0] -% candidateMinX < 0 or candidate.pos[0] -% candidateMaxX > 0) continue;
if (candidate.pos[1] -% candidateMinY < 0 or candidate.pos[1] -% candidateMaxY > 0) continue;
newCandidates.appendAssumeCapacity(candidate);
}
fillRecursively(wx, wy, preMap, newCandidates.items, worldSeed, newRelX, newRelY, newWidth, newHeight);
const pruned = pruneInterpolationCandidates(main.stackAllocator, wxMin, wyMin, wxMax, wyMax, biomeCandidates);
defer main.stackAllocator.free(pruned);
fillRecursively(wx, wy, preMap, pruned, worldSeed, newRelX, newRelY, newWidth, newHeight);
}
}
}
Expand Down
Loading